The present invention relates generally to gas, vapor and particulate detection devices, and more particularly, to a remote transmitting gas, vapor and/or particulate monitor apparatus that may be used as a warning device for site remediation.
Gases and vapors may be sensed by an organic vapor monitor as is known in the art. Traditionally, the monitoring of gases and vapors has been performed manually with hand-held gas and vapor detectors. The hand-held devices require constant operator attention. Since more than one detector may be needed at a site, the hand-held units would each require an operator and the expense to the site owner would rise accordingly. Additionally, when operators are in or near a contaminated site using the detectors, there may be a potential health hazard to the operators. The "fenceline" is the border or perimeter around a site within which exists potentially contaminated conditions and outside of which is considered to be safe or below some predetermined designated health level. The goal of fenceline monitoring is to ensure that only air of acceptable quality impacts the downwind population. In the course of site remediation, there often exists the potential for volatile organic compound or inorganic compound or other toxic gas or particulate release via the air pathway. Monitoring of potential releases is typically the responsibility of the site health and safety officer who, in addition to protection of on-site worker safety, must protect public health from exposure to site-derived contaminants.
Traditional compound-specific air characterization work is often performed prior to remediation as part of the initial remedial investigation to determine the type and concentration of compounds in the vicinity of the site. These background air investigations are useful in assessing site air quality under existing conditions and are often the only reliable source of data for subsequent risk evaluations performed for the air pathway. During implementation of a chosen remedial technology, compound-specific upwind/downwind ambient air sampling may be performed to assess the potential for air quality degradation attributable to the clean-up effort. While the compound-specific data provided by sampling is indispensable in characterizing the health impact of the site relative to the air pathway, these methods are not applicable to the on-going daily monitoring required during clean-up. In addition to the need for trained air pollution professionals with specialized test equipment on site, the analytical costs over time would be prohibitive and test results would not be available in a suitable time frame to protect the public from an acute release. Therefore, there is a need for a reliable real time air monitoring system which could be operated by site personnel at a reasonable cost during extended site remediation.
The present invention, a remote transmitting fenceline monitor apparatus is designed to fill this need. The monitor may include an organic vapor monitor that utilizes a photoionization detector or in an appropriate application a real time particulate sampler or other gas vapor monitor utilizing alternate sensors. These items and equivalent or similar devices may be purchased off the shelf to measure a wide range of organics, inorganics and particulates. The monitor may contain means for producing a signal, such as an alarm, which triggers when a predetermined health action level has been met. Health action levels are selected based on the specific compound types and concentration derived from the previously performed air characterization study. The known health impact and published threshold limit values or permissible exposure limits are also considered in selecting a health action limit representative of the anticipated group of site compounds in the air.
Unique circuitry may be added to the monitor which permits the organic vapor monitor, particulate sampler or other measurement device to transmit an alarm signal via a transmitter such as a walkie-talkie without operator intervention. Therefore, at the potentially contaminated site, an on-site operator is not needed once the equipment has been set up. By providing a health and safety officer with a second receiver (e.g.-walkie-talkie) of the same frequency, perimeter air quality can be monitored within the transmitting range, on or off site. Other transmitting means may also be used to convey the signal to a remote location. The monitors may be portable, and contained in a weather-proof enclosure capable of extended operation through a rechargeable battery.
Fenceline monitors are usually deployed on the downwind site perimeter as a buffer between the active area of remediation and the general population. In addition to daily calibration with a standard reference gas or by other suitable means, the fenceline monitors may be maintained downwind by either monitoring data from an on-site meteorological station, by observing a windsock, or by listening to local weather reports. Alternatively the fenceline monitors may be sited at multiple locations to encircle the site. The adjustable alarm may be supplemented by an internal data logger which enables storage of data points at predetermined time intervals. This feature provides the added benefit of storage and summarization of ambient concentrations. Such information may be retrieved at a later date and used to demonstrate acceptable perimeter air quality to the public and regulatory officials on an on-going basis.
The foregoing and other objects and advantages will become more apparent when viewed in light of the accompanying drawings and following detailed description.